What Is This Knock/slap/tick My Engine Is Making?

[rollex]

I posted a thread a while ago and also asked a workshop who tuned my car but no one really said anything as it was barely audible back then. Anyway this noise is getting worse and seems to be coming from rear of engine, the speed of the sound suggests it is a single valve/piston or something like that. It sounds too light to be a big end bearing but it could still be one.

I've tried the screwdriver in the ear trick to see if I can figure out where it is coming from but can't narrow it down, the noise definitely doesn't sound good though, like piston slap.

This noise has been audible to me for almost a year but in the last month or so has gotten worse and I can hear it at low revs where the engine isn't loaded up, before I could only hear it on boost where it was impossible to record.

Can someone recommend a place to get an oil analysis done in SA? I want to get the oil analysed to find out if it is bearings or not. How good is an oil analysis for determining this? Oil has been in the motor for about 1800 kms

Here are some videos of the noise (clutch is in):

Edited 10/06/15 10:45 AM by rollex

[Ralph Wiggum]

Exhaust leak.

[rollex]

that's what KPM thought and they tightened up every single bolt (they said exhaust cover was loose and 2 bolts in the turbo housing were missing) but the noise was 100% unchanged afterwards.

I've tried jacking up the turbo exhaust cover with stuff holding it in place to arrest any vibration with zero change, it has definitely gotten worse in the last few days as well.

I don't think it is the exhaust as the frequency changes with rpm, it sounds like a machine gun at 5000rpm

Edited 10/06/15 10:58 AM by rollex

[Ralph Wiggum]

Exhaust leak between the head and manifold will change frequency as the revs go up. All the retorques in the world wont sort out a blown gasket.

Missing bolts in the turbine housing are generally a sign of a cracked housing,replacing them wont prevent the noise.

[rollex]

Does an exhaust leak tend to sound like a metal on metal slap like that?

[shaness8]

Flywheel?

[Ralph Wiggum]

Does an exhaust leak tend to sound like a metal on metal slap like that?

Yes it can do, the metal gasket gets blown around and can make quite a bit of noise. Back pressure at the port is relatively high due to the turbo so the noise will also increase as revs/load goes up.

[rollex]

Ok I'll take the heat shield off and see if there is obvious leaks or I can fit a feeler gauge in the gaps.

Thanks

[jas98]

Mine was allot louder......extremely loud. But was exhaust leak at number 1 cylinder and also others were leaking a bit too...quiet as now. Only a slightvtappet ick for half a second at start up which ain't bad for 280 000 ks

[rollex]

Was the gasket between head and manifold had failed completely, the dump gasket and a few others were average so we replaced all of them. All the noise are gone now, it also doesn't randomly get laggy anymore.

So much better to drive, enjoying it again and don't want to burn the car anymore.

#winning